In 1965, Hurricane Betsy demonstrated that a major hurricane could overtop the earthen levees of the 17th Street Canal. So the Army Corps of Engineers recommended two cost-effective plans which were 1) raising the height of the canal walls or 2) installing floodgates at the canal's mouth at the lakefront. The Corps felt both could provide reliable hurricane surge protection.
Since the cost for both approaches was about the same, the Corps ultimately elected to raise the canal walls using I-walls (concrete capped steel sheet pilings). The Corps did this partly because the local sponsors (Orleans Levee Board and the Sewage and Water Board) preferred it. The OLB and SWB viewed the floodgates plan as incompatible with their interior drainage responsibilities. (Note the gates plan did not include auxiliary pumps like those in place today.)
On August 29, 2005 at about 9:45 a.m, a monolith (30-foot long section of the concrete floodwall) failed sending torrents of water into New Orleans's Lakeview neighborhood. The water level in the Canal at the time of failure was about 5 feet lower than the top of the wall. The breach quickly expanded into a 450 foot wide gap through which storm surge water poured, killing hundreds (directly and indirectly), destroying hundreds of residences, and causing millions of dollars in property damage. Thirty-one (31) bodies were recovered from areas directly flooded.
Today, the adjacent land is vacant of homes, buildings and trees. Many foundations or slabs where homes once stood are all that remain. The repaired breach site now consists of a different sturdier design called a T-wall. Three times more expensive to build, the new wall is easily differentiated because of its different texture and different color. It is also two feet thicker.
Post-disaster studies conclude that the breach was due to steel sheet pilings driven to depths that were too shallow. Sadly, in recommending the I-walls with such short sheet pilings, the Corps had relied upon a poorly executed and misinterpreted study it had conducted near Morgan City in 1988. At a savings of $100,000,000, the Corps wrongly concluded it could short-sheet the steel pilings of the 17th Street Canal driving them to depths of not more than 17 feet instead of between 31 and 46.
In January of 2008, Federal Judge Stanwood Duval, of the US District Court for Eastern Louisiana, held the US Army Corps of Engineers responsible for defects in the design of the concrete floodwalls constructed in the levees of the 17th Street Canal; however, the agency could not be held financially liable due to sovereign immunity provided in the Flood Control Act of 1928.